The increasing use of light vans and other such carrier vehicles to carry people increases the need of means to facilitate the boarding of those relatively high vehicles, especially when such vehicles are used for transporting people having mobility problems. Such means are also more than useful when the vehicle is used to transport goods that may require a parcel truck or a hand truck to carry them in and out of the vehicle.
Boarding means for light carrier vehicles can generally be discriminated in two categories: lifts and ramps.
In U.S. Pat. No. 5,228,538, issued on Jul. 20, 1993 and entitled "Passenger Lift with an Electric Safety Interlock", Jules M. Tremblay describes a passenger lift to help people into and out of vans and buses. Tremblay's lift comprises a platform pivotally connected to the vehicle by a pair of spaced armatures. The lift also includes mechanisms to move the platform from a storage position to a horizontal position as well as to operate the platform.
Tremblay's lift possesses drawbacks common to most lifts. First, the lifting and storing mechanisms are bulky and require passenger and/or storage room. Secondly, since the lift is attached to the floor of the vehicle near one of the doors thereof, it obstructs the passageway to the passengers who want to board the vehicle without using the lift. Moreover, the lift cannot be easily moved to facilitate boarding the vehicle through another entrance.
Ramps are usually less obstrusive since they usually do not include a lifting mechanism. An example of such a ramp is described in U.S. Pat. No. 5,636,399, which was issued to Tremblay et al. on Jun. 10, 1997, and entitled "Movable Ramp Assembly". The proposed ramp assembly includes mounting structures, guides and a deployment mechanism to store and deploy the ramp.
A first drawback of this ramp assembly is that the deployment mechanism is relatively complex and therefore prone top break.
Another drawback of Tremblay's ramp assembly is that it requires mounting structures to be fixedly mounted to the vehicle and thus cannot be moved from between different entrances of the vehicle according to boarding requirements.